Incandescent electric lamp



T. D'AVIS.

INCANDESCENT ELECTRIC LAMP.

APPLICATION FILED NOV. 14. I917.

1,348,350. a t dAug- 3,1920.

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w 14 14 I 1'? w 1'7 9 3 wmwtw UNITED STATESL" PATENT OFFICE.

rnnaou Davis, or NEW YORK, N. Y.

, INCANDESCENT ELECTRIC LAMP.

Specification of Letters Patent.

Application filed November 14, 1917. Serial No. 202,048.

To-all whom it may concern:

Be it known that I, THERON DAVIS, a citizen of the United States, and a resident of the city, county, and State of New York, have invented a new and useful Improvement in Incandescent Electric Lamps, of which the duce a simple and more stable lamp support for the light filament by using "a strong re-. fractory and preferably transparent or translucent substance that will not only withstand the heat generated in the light fila ment but will itself give off luminosity at the temperature of incandescence or when highly heated, thus producing a better light. The further object of my invention is to construct and arrange a filament support and filament so that a lamp, either of high or low candle power can be made with less labor and cost than is necessary in lamps of the usual type. Still another object of my invention is to construct and arrange the light filament so that a plurality of these filaments can be contained in a single globe and independently connected, thus producing a lamp of high efficiency by the concentration of the several elements and making the arrangement such that in case one light element is burned out or destroyed the other will continue to give off light so thatthe lamp is not wholly destroyed by the destruction of or cutting out of one of its elements.

In carrying out my invention I anchor a sheet or strip of highly refractory transparent or translucent material such as mica,

to the lamp stem, carry my leading in wires to the lamp in a usual or preferred way, winding the filament around or upon the said refractory substance and thus it will be seen that the light element is unusually stable and the filament is not likely to be destroyed by any vibrations to which incandescent electric lamps are likely to be subjected. This support and the manner of winding the filament thereon can be arranged in several ways and I have shown preferred means of supporting and arranging the filament.

Reference is to be had to the accompanying drawings forming part of this specificarefer to similar "vlews.

Patented Aug: 3,1920.

tion in which similar reference characters Figure 1 is a diagrammatic elevation of an ncandescent electric lamp embodying my 1m rovements.

1g. 2 1s a similar view taken at right an les to the view shown in Fig. 1.

1 3 is an elevation similar to F i 2 but s 0w1ng a modifioation'of the light element.

Fig. 4 is a similar diagrammatic elevation showing another modification of the lamp and a duplication of the light elements.

F 1g. 5 IS a detailed section showing one way of anchoringthe refractory filament su porting strip.

11 the drawin s I have shown the usual form of incandescent electric lamps in which the globe 9 and socket 10 of conventional shape and construction are used but so far as my invention is concerned the character of the globe'and socket is immaterial.

, I have shown a lamp provided with the customary stem 11 which at its inner end' is formed into a holder 12 to receive the mica strips 14 which form the support for the filament presently referred to. These stri s 14 are held in parallel relation and are pre erably although not necessarily rectangular'in form as shown in Fig. 1 and their outer ends enter the socket or holder 12 and the strips can beperforated at 15 so that the glass at this point can be fused as shown at 16 Fig. 5 and thus pass through the perforations and fasten the strips 14 to the holder. Obviously the strips can be supported, however, in any convenient manner which will hold them in the right relapa rts throughout the several tion to the other members of the lamp without affecting the invention.

The lamp is shown provided with line wires a and b which can be arranged in the customary or preferred way as my invention does not relate to this part of the lamp. The filament 17, which in my experiments has been tungsten wire and which material.

continues to be satisfactory, is connected to the'wlre a, then led downward between the two strips 14, as shown at 0 and is returned by spirally winding it around the two strips as shown at d, finally connecting with the wire b. While my invention is not confined to this particular way of supporting the filament on the strips 14, I find this to be an advantageous arrangement because it can;

be easily carried out and the return windings serve to bind the two strips together in such a manner that they cannot be displaced. Before winding the strips can be rubbed or dulled on the edges which tends to soften them in case mica is used and thus a better seat is provided for the filament and the strips are prevented from cutting it. \Vhen arranged in this way and the filament is snugly and permanently wound it seats itself in the edges of the strips and by this arrangement it is prevented from slipping afterward and making a short circuit. This arrangement also enables the filament wire to be wound with its members in close relation but not in contact and thus less space is occupied to provide for a given length of filament and the heat created by the resistance of the filament to the current is concentrated around the several members of the filament and in the filament support so that a higher temperature and consequently higher incandescence is produced by a given current than is the case where the filament members are widely separated as in many forms of incandescent electric lamps.

In some cases inert gases are inserted in the lamp globes to serve to hold and concentrate and cause a centralization of heat about the filament but in this arrangement I secure a satisfactory effect without the use of gases although obviously inert or other gases can be used if desired.

In Fig. 3 I have shown a form of lamp in which the concentration of heat can be still further obtained and in which the members of the filament are still more permanently held in place. I accomplish this result by simply covering the opposite sides of the light element with sheets 18 of mica or like substance which are secured at one end in the holder 12 and which at the other end can be held in place by a cap 19 which is fastened to the strips.

In Fig 4 I have shown a duplication of the light elements but as will be presently seen any desired number of these elements can be secured in a single globe. As shown a duplicate holder is illustrated and two separate elements 20 and 21 are secured in the holder in the manner described. By reference to the drawing it will be seen that each element is individually connected to the leading in wires. For instance the right hand element 20 has one end of the filament 17 connected as shown at e to the leading in wire a while the opposite end of the filament connects as shown at f to the leading in wire I) and the element 21 issimilarly and individually connected. In this arrange ment it will be noticed that if one light ele' ment gives out for any reason other than the cutting off of current of the lamp the other light element will continue to give out light. It will be further noticed that by this arrangement I get at least double the amount of light, with of course double the amount of current, than would be obtained from a lamp having the same length of filament and I get the advantage of concentrating this amount of light at a single point which for many purposes is desirable, such as for instance in motion picture projection. By combining these several elements in close relation I get a concentration of heat above referred to which seems to increase the efliciency of the lamp by producing higher incandescence of the filament with a given amount of current. The heat and consequently the light resulting will be governed by the proximity of the several light elements as well as by the number of such elements.

From the foregoing description it will be seen that my invention has nothing to do with the general construction of the lamp but lies in the lighter lamp element, either singly or in combination and while I have used in my experiments mica as a filament support and tungsten as a filament I wish it distinctly understood my invention permits the use of other refractory transparent,-

translucent or incandescing materials which may be found suitable, such for instance as quartz glass or other materials and the use of other forms of filament wire if found advisable.

I am aware that other forms of more or less rigid support for incandescent electric lamp filaments have been used but I do not know any support for such filaments has been used prior to my invention in which the support is a highly refractory transparent or translucent or incandescing material came in direct contact with the light filament and served to support and space the filament members.

In some cases attempts have been made to use glass as a direct support for the wire or filament, but these attempts have not resulted in practical lamps for the reason that glass is too fragile and too easily fused. It is necessary to have a structure reasonably tough and infusible at or near the temperature produced by the incandescing of the lamp filament.

For some purposes it is desirable to preserve the flat shape of the light element as the whole element tends to become luminous and throws practically a solid beam of light. This effect is of course intensified where the light element is duplicated.

While my invention as above described is intended for use in a globe from which the air has been ,more or less exhausted it is obvious that the advantages of construction and heat. concentration above pointed out would obtain with materials other than mica and tungsten which were adapted for open air use.

I am aware that certain "refractory substances, particularly mica, has a tendency to disintegrate when frequently or continuously subjected to a high temperature in the open air or in the presence of oxygen and p 3. An incandescent lamp comprising a flat "highly refractory support, a filament wound similar gases but my experiments have shown this is not the.case where mica is 1. A'lamp element for incandescent e1ectric lamps comprising a thin flat highly'refractory support formed of two thin sheets of material placed opposite each other, and

a filament extending between the sheets and wound externallyupon them.

' 2. An incandescent electric lamp comprising a containing globe, an insulating. stem globe which is filled with an thin fiat highly refractory support fitting within the socket of the stem, and a filament wound spirally and externally on the suport. v

externally upon the support, and-strips of I i transparent material covering the wider sides of the structure.

7 4. An incandescent electric lamp comprising'a containing globe, a thin flat highly refractory support carried within the globe, a filament wound externally upon the support, andta transparent cover fitting over the filament and support.

THERON DAVIS. Y

Witnesses:

..;WARREN B. HU'rcHINsoN,

M. G. O D0NNELL. 

